Substrate cleaning apparatus and substrate cleaning method

ABSTRACT

A processing solution containing solvent and solute is supplied onto a substrate ( 9 ). The processing solution transforms into a particle retention layer as a result of at least part of the solvent being volatilized from the processing solution and causing the processing solution to solidify or harden. The particle retention layer is removed from the substrate ( 9 ) by supplying a removal liquid onto the substrate ( 9 ). A solute component contained in the particle retention layer is insoluble or poorly soluble in the removal liquid, whereas the solvent is soluble. The solute component contained in the particle retention layer has the property of being altered to become soluble in the removal liquid when heated to a temperature higher than or equal to an alteration temperature. The removal liquid is supplied after the formation of the particle retention layer, without undergoing a process of alternating the solute component.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/471,629, filed Jun. 20, 2019, which is a 35 U.S.C. § § 371national phase conversion of PCT/JP2017/046090, filed Dec. 22, 2017which claims priority to Japanese Patent Application Nos. 2017-000676and 2017-241845, filed Jan. 5, 2017 and Dec. 18, 2017, respectively, thecontents of both of which are incorporated herein by reference. The PCTInternational Application was published in the Japanese language.

TECHNICAL FIELD

The present invention relates to a technique for removing variouscontaminants adhering to substrates, residues of materials such asprocessing solutions or resists from upstream processes, variousparticles, or the like (which are hereinafter simply referred to as“particles”) from semiconductor wafers, glass substrates for liquidcrystal displays, glass substrates for organic EL displays, glasssubstrates for plasma displays, optical disk substrates, magnetic disksubstrates, magneto-optical disk substrates, glass substrates forphotomasks, substrates for solar cells, or the like (which arehereinafter simply referred to “substrates”).

BACKGROUND ART

A substrate manufacturing process conventionally includes a cleaningprocess for removing particles from a substrate. In the cleaningprocess, in most cases, particles are removed physically from asubstrate by supplying a cleaning liquid such as deionized water(hereinafter, expressed as “DIW”) to the substrate, or removedchemically from a substrate by supplying a chemical solution to thesubstrate.

However, miniaturization and complication of patterns make the patternsmore susceptible to physical or chemical damage. In view of this, forexample with the technique disclosed in Japanese Patent ApplicationLaid-Open Gazette No. 2014-197717, particles are separated from asubstrate by supplying a top coat solution onto the substrate and thenusing contractile force generated during solidification or hardening ofthe top coat solution. Thereafter, a topcoat and particles are removedfrom the substrate by dissolving the top coating in a removal liquid.

Meanwhile, according to Japanese Patent Application Laid-Open GazetteNo.

2015-95583, a top coat film formed of a top coat solution on a substrateis stripped off with DIW from the substrate. Then, a dissolutionprocessing solution is supplied onto the substrate so that the strippedtop coat film is dissolved in the solution on the substrate and removed.Note that the fourth embodiment of Japanese Patent Application Laid-OpenGazette No. 2015-95583 describes a case in which, when a substrate hasno pattern formed thereon, the film is stripped off with DIW from thesubstrate, and the DIW further continues to be supplied so that the filmis removed without being dissolved in the solution.

Incidentally, in the case where a film formed on a substrate (this filmis hereinafter referred to as a “particle retention layer”) is removedfrom the substrate while being dissolved in a solution, particles mayfall off from the particle retention layer and adhere again to thesubstrate. Also, in the case where the particle retention layer is notdissolved in a solution, it is not easy to remove the particle retentionlayer from the substrate. In particular, as indicated by Japanese PatentApplication Laid-Open Gazette No. 2015-95583, when a substrate has apattern formed thereon, it is difficult to remove the particle retentionlayer from the substrate without dissolving the particle retention layerin a solution. The reason for this is considered to be because theparticle retention layer remains in clusters of a certain size on thepattern.

SUMMARY OF INVENTION

It is an object of the present invention to improve a particle removalrate with a technique that uses a particle retention layer to removeparticles from a substrate.

A substrate cleaning apparatus according to a preferable embodiment ofthe present invention includes a processing solution supply part thatsupplies a processing solution containing solvent and solute, onto asubstrate, a removal liquid supply part that supplies a removal liquidonto the substrate, and a controller that controls the processingsolution supply part and the removal liquid supply part. The solvent hasvolatility. The processing solution transforms into a particle retentionlayer as a result of at least part of the solvent being volatilized fromthe processing solution supplied onto the substrate and causing theprocessing solution to solidify or harden. A solute component that isthe solute contained in the particle retention layer or that is derivedfrom the solute is insoluble or poorly soluble in the removal liquid.The solvent is soluble in the removal liquid. The solute componentcontained in the particle retention layer has a property of beingaltered to become soluble in the removal liquid when heated to atemperature higher than or equal to an alteration temperature.

The particle retention layer is removed from the substrate under controlof the controller that, after the particle retention layer is formed onthe substrate, controls the removal liquid supply part to supply theremoval liquid to the particle retention layer without undergoing aprocess of altering the solute component of the particle retentionlayer. The substrate cleaning apparatus can improve the particle removalrate.

A substrate cleaning apparatus according to a more preferable embodimentof the present invention further includes a heating part that heats theparticle retention layer. The controller controls the heating part toheat the particle retention layer up to a temperature lower than thealteration temperature before the removal liquid is supplied to theparticle retention layer.

In a preferable example, the processing solution supply part suppliesthe processing solution to an upper face of the substrate held in ahorizontal position, and the heating part heats the particle retentionlayer by supplying heated deionized water to a lower face of thesubstrate.

In another preferable example, the processing solution supply partsupplies the processing solution to an upper face of the substrate heldin a horizontal position, and the heating part heats the particleretention layer by supplying heated deionized water to the upper face ofthe substrate.

In yet another preferable example, the removal liquid supply partsupplies the removal liquid that is heated up to a temperature lowerthan the alteration temperature, onto the substrate.

In yet another preferable example, the processing solution supply partsupplies the processing solution that is heated up to a temperaturelower than the alteration temperature, onto the substrate.

A substrate cleaning apparatus according to another preferableembodiment of the present invention further includes another heatingpart that heats the substrate up to a temperature lower than thealteration temperature before or in parallel with the supply of theprocessing solution to the substrate.

Preferably, the substrate cleaning apparatus further includes asubstrate holder that holds a substrate. Operations from supplying theprocessing solution to the substrate to supplying the removal liquid tothe substrate are performed while the substrate is held by the substrateholder.

The present invention is also intended for a substrate cleaning method.A substrate cleaning method according to a preferable embodiment of thepresent invention includes a) supplying a processing solution containingsolvent and solute, onto a substrate, and b) supplying a removal liquidonto the substrate. The solvent has volatility. In the operation a), theprocessing solution transforms into a particle retention layer as aresult of at least part of the solvent being volatilized from theprocessing solution supplied onto the substrate and causing theprocessing solution to solidify or harden. A solute component that isthe solute contained in the particle retention layer or that is derivedfrom the solute is insoluble or poorly soluble in the removal liquid,and the solvent is soluble in the removal liquid. The solute componentcontained in the particle retention layer has a property of beingaltered to become soluble in the removal liquid when heated to atemperature higher than or equal to an alteration temperature. After theoperation a), the particle retention layer is removed from the substrateby performing the operation b) without undergoing a process ofalternating the solute component of the particle retention layer.

A substrate cleaning method according to a more preferable embodiment ofthe present invention further includes c) heating the particle retentionlayer up to a temperature lower than the alteration temperature. Theoperation c) is performed between the operation a) and the operation b).

In a preferable example, in the operation a), the processing solution issupplied to an upper face of the substrate held in a horizontalposition, and in the operation c), the particle retention layer isheated by supplying heated deionized water to a lower face of thesubstrate.

In another preferable example, in the operation a), the processingsolution is supplied to an upper face of the substrate held in ahorizontal position, and in the operation c), the particle retentionlayer is heated by supplying heated deionized water to the upper face ofthe substrate.

In yet another preferable example, in the operation b), the removalliquid that is heated up to a temperature lower than the alterationtemperature is supplied onto the substrate.

In yet another preferable example, in the operation a), the processingsolution that is heated up to a temperature lower than the alterationtemperature is supplied onto the substrate.

In a substrate cleaning method according to another preferableembodiment of the present invention, the substrate is heated up to atemperature lower than the alteration temperature before or during theoperation a).

In the above-described substrate cleaning method, preferably, operationsfrom supplying the processing solution to the substrate to supplying theremoval liquid to the substrate are performed while the substrate isheld by a same substrate holder.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view illustrating a configuration of a substratecleaning system;

FIG. 2 illustrates a configuration of a substrate cleaning apparatus;

FIG. 3 illustrates a flow of substrate cleaning;

FIG. 4 illustrates heat treatment performed by the substrate cleaningapparatus;

FIG. 5 illustrates the results of measurement using the QCM method;

FIG. 6 illustrates the results of measuring a PRE (particle removalrate);

FIG. 7 illustrates the results of measuring the PRE;

FIG. 8 illustrates the results of measuring the PRE;

FIG. 9 illustrates the results of measuring the PRE;

FIG. 10 illustrates the results of measuring the PRE;

FIG. 11A is a conceptual diagram illustrating a particle retentionlayer;

FIG. 11B is a conceptual diagram illustrating how the particle retentionlayer is removed;

FIG. 12 illustrates part of another exemplary operation performed by thesubstrate cleaning apparatus;

FIG. 13 illustrates part of yet another exemplary operation performed bythe substrate cleaning apparatus;

FIG. 14 illustrates part of yet another exemplary operation performed bythe substrate cleaning apparatus;

FIG. 15 illustrates part of yet another exemplary operation performed bythe substrate cleaning apparatus;

FIG. 16 illustrates part of yet another exemplary operation performed bythe substrate cleaning apparatus; and

FIG. 17 illustrates part of yet another exemplary operation performed bythe substrate cleaning apparatus.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a plan view illustrating a configuration of a substratecleaning system 1 according to an embodiment of the present invention.The substrate cleaning system 1 includes a carrier holder 2, a substratetransfer part 3, an indexer robot 101, a center robot 102, foursubstrate cleaning apparatuses 4, and a controller 10. As will bedescribed later, the controller 10 may be regarded as part of thesubstrate cleaning apparatuses 4.

Carriers 90 are containers capable of stacking and housing a pluralityof substrates 9. The carriers 90 house unprocessed substrates 9 orprocessed substrates 9. The substrates 9 according to the presentembodiment are semiconductor substrates, i.e., so-called wafers. Thecarrier holder 2 supports a plurality of carriers 90.

As illustrated conceptually by broken-line arrows in FIG. 1, the indexerrobot 101 is capable of transporting substrates 9 to an arbitraryposition with its arms that are pivotable and movable back and forthwhile holding the substrates 9. The indexer robot 101 is also movable inthe up-down direction while holding the substrates 9. Unprocessedsubstrates 9 in a carrier 90 that is placed on the carrier holder 2 aretransported to a path 31 of the substrate transfer part 3 by the indexerrobot 101. The path 31 functions as a buffer that temporarily stores aplurality of substrates 9.

Processed substrates 9 placed on the path 31 are transported by theindexer robot 101 into a carrier 90 that is placed on the carrier holder2. For convenience of illustration, the path 31 is indicated by a dasheddouble-dotted line in FIG. 1. The center robot 102 is capable oftransporting substrates 9 to an arbitrary position with its arms thatare pivotable and movable back and forth while holding the substrates 9.With this operation, the center robot 102 transports the substrates 9between the path 31 of the substrate transfer part 3 and a substratecleaning apparatus 4.

FIG. 2 illustrates a configuration of one substrate cleaning apparatus4. The substrate cleaning apparatus 4 includes a substrate holder 42, asubstrate rotation mechanism 41, a cup 43 that surrounds the substrateholder 42, a supply part 44, a heating part 46, and a chamber 47. Atleast the substrate holder 42, the cup 43, and the heating part 46 arelocated within the chamber 47. The substrate holder 42 includes a spinbase 421, chucks 422, and a first shaft 423. The spin base 421 has adisk-like shape centered on a central axis J1 of the first shaft 423.The plurality of (e.g., six) chucks 422 is disposed on the upper face ofthe outer peripheral portion of the spin base 421. An unprocessedsubstrate 9 transferred from the center robot 102 is placed on thechucks 422. The substrate 9 is held in a horizontal position by thesubstrate holder 42.

The first shaft 423 is connected to the lower face of the spin base 421and extends downward from the spin base 421. The central axis J1 of thefirst shaft 423 passes through the center of the substrate 9. Thesubstrate rotation mechanism 41 rotates the first shaft 423. This causesthe substrate holder 42 and the substrate 9 to rotate about the centralaxis J1. In the present embodiment, the substrate rotation mechanism 41is a motor having the first shaft 423 as its rotary shaft. The substraterotation mechanism 41 may have another structure. The substrate holder42 may also adopt another structure, and for example, may be structuredto adsorb the lower face of the substrate 9.

The heating part 46 includes a heating plate 461, a second shaft 462,and a plate elevating mechanism 463. The heating plate 461 has adisk-like shape that extends in a direction perpendicular to the centralaxis J1. The heating plate 461 is located above the spin base 421. Whena substrate 9 is held by the chucks 422, the heating plate 461 islocated between the substrate 9 and the spin base 421. A heater 464 isprovided in the heating plate 461. The second shaft 462 extends downwardfrom the center of the heating plate 461 along the central axis J1. Thefirst shaft 423 is hollow, and the second shaft 462 is located insidethe first shaft 423, passing through the first shaft 423. The plateelevating mechanism 463 moves the second shaft 462 up and down. Thiscauses the heating plate 461 to move up and down.

The supply part 44 includes a processing solution supply part 441, aremoval liquid supply part 442, and a rinsing liquid supply part 443.The processing solution supply part 441 includes a processing solutionsupply source 451, a first nozzle 452, and a first nozzle movingmechanism, which is not shown. The removal liquid supply part 442includes a removal liquid supply source 453, a second nozzle 454, and asecond nozzle moving mechanism, which is not shown. The rinsing liquidsupply part 443 includes a rinsing liquid supply source 455, the secondnozzle 454, the second nozzle moving mechanism, and a lower nozzle 456.The second nozzle 454 and the second nozzle moving mechanism areincluded in both of the removal liquid supply part 442 and the rinsingliquid supply part 443.

The first nozzle moving mechanism locates the first nozzle 452selectively at either an opposing position that opposes an upper face 91of the substrate 9 or a standby position that is spaced from thesubstrate 9 in the horizontal direction. The second nozzle movingmechanism locates the second nozzle 454 selectively at either theopposing position that opposes the upper face 91 of the substrate 9 andanother standby position that is spaced from the substrate 9 in thehorizontal direction. The lower nozzle 456 is provided in the center ofthe heating plate 461 and opposes a lower face 92 of the substrate 9.The second shaft 462 includes a flow path 465 that is connected to therinsing liquid supply source 455.

Valves are provided appropriately between the processing solution supplysource 451 and the first nozzle 452, between the second nozzle 454 andeach of the removal liquid supply source 453 and the rinsing liquidsupply source 455, and between the rinsing liquid supply source 455 andthe lower nozzle 456. The controller 10 controls the first and secondnozzle moving mechanisms and opening and closing of each valve. Theejection of the processing solution from the first nozzle 452, theejection of the removal liquid from the second nozzle 454, the ejectionof the rinsing liquid from the second nozzle 454, and the ejection ofthe rinsing liquid from the lower nozzle 456 are controlled by thecontroller 10 controlling the valves.

The controller 10 also controls other constituent elements such as thesubstrate rotation mechanism 41, the substrate holder 42, and theheating part 46. Thus, some functions of the controller 10 may beregarded as being included in the substrate cleaning apparatus 4. Partof the controller 10 may be provided in the chamber 47 as a constituentelement dedicated for each substrate cleaning apparatus 4.

FIG. 3 illustrates a flow of cleaning the substrates 9 in the substratecleaning apparatus 4. Operations illustrated in FIG. 3 are performed bythe controller 10 controlling constituent elements such as the substraterotation mechanism 41, the heating part 46, the processing solutionsupply part 441, the removal liquid supply part 442, and the rinsingliquid supply part 443.

First, an unprocessed substrate 9 in a carrier 90 is transported intothe substrate cleaning apparatus 4 by the indexer robot 101 and thecenter robot 102. In the substrate cleaning apparatus 4, the outer edgeof the substrate 9 is held by the chucks 422 with the upper face 91,i.e., one main surface, of the substrate 9 facing upward.

The processing solution supply part 441 supplies a processing solutionto the upper face of the substrate 9 held in a horizontal position (stepS11). Specifically, the first nozzle 452 is moved to the center of theupper face 91 of the substrate 9, and the processing solution is ejectedfrom the first nozzle 452 toward the center of the upper face 91. Theprocessing solution is supplied in the form of liquid columns or in theform of droplets that naturally drop from the nozzle to the substrate 9.The processing solution according to the present embodiment containspolymer as solute and an organic liquid having volatility as solvent.Here, “having volatility” refers to having higher volatility than water.In the case of supplying the processing solution, the substrate rotationmechanism 41 rotates the substrate 9 together with the substrate holder42 about the central axis J1 at a speed of, for example, ten to severaltens of rotations per minute (rpm), so that the processing solutionspreads over the upper face 91 of the substrate 9. Thereafter, thesubstrate 9 is rotated at a high speed of 500 to 1500 rpm, and a surplusof the processing solution is dispersed from the substrate 9 andreceived by the cup 43.

When the processing solution has spread uniformly over the upper face 91and the solvent has been volatilized to some extent, the processingsolution solidifies or hardens into a solid layer. As a result,particles on the substrate 9 are retained in that layer. Hereinafter,such a layer that is obtained as a result of the processing solutionbeing altered into a solid is referred to as a “particle retentionlayer.”

Here, “solidification” refers to, for example, solidification of thesolute due to forces or the like acting between molecules or atoms.Also, “hardening” refers to, for example, solidification of the solutedue to chemical changes such as polymerization or crosslinking.Accordingly, “solidification or hardening” means “solidification” causedby various factors. Note that it is sufficient for the processingsolution to solidify or harden to such an extent that it can retainparticles, and the solvent does not necessarily have to be completelyvolatilized.

Preferably, the processing solution shrinks and transforms into theparticle retention layer in accordance with the volatilization of thesolvent. This causes particles on the substrate 9 to be separated fromthe surface of the substrate 9 by the force received from the particleretention layer.

Next, the substrate 9 is heated by the heating part 46 (step S12). Theparticle retention layer is considered to further shrink due to theheating. The heating of the substrate 9 also means the heating of theparticle retention layer. Step S12 is not an absolute necessity. If stepS12 is not performed, a state in which the substrate 9 is held by thesubstrate holder 42 is maintained for a predetermined period of time.

In the case of heating the substrate 9, the temperature of the heatingplate 461 is increased to a predetermined value by the heater 464 in theheating plate 461. As illustrated in FIG. 4, the heating plate 461 ismoved upward by the plate elevating mechanism 463 so that the upper faceof the heating plate 461 lifts up the substrate 9 in contact with thelower face 92 of the substrate 9. Accordingly, the substrate 9 is heatedwith the heat from the heating plate 461. Alternatively, the substrate 9may be heated by bringing the heating plate 461 into close proximity tothe lower face 92 of the substrate 9, or may be heated using both of thestates in which the heating plate 461 is in contact with the lower face92 of the substrate 9 and in which the heating plate 461 is in closeproximity thereto.

The supply of the processing solution in step S11 and the heating instep S12 may be performed in parallel. That is, the heating may beperformed after the solidification or hardening of the processingsolution, or may be performed during the volatilization of the solvent.At the time of forming particle retention layer, usually only part ofthe solvent contained in the processing solution is volatilized, but thesolvent may almost completely be volatilized from the processingsolution. That is, the volatilization of at least part of the solventcauses the solute component of the processing solution to solidify orharden.

In the following description, a component of the particle retentionlayer that corresponds to the solute in the processing solution isreferred to as a “solute component.” The solute component may be thesolute itself in the processing solution, or may be derived from thesolute, e.g., obtained as a result of chemical changes or the like.According to the present embodiment, the solute component of theparticle retention layer is altered to become soluble when heated to atemperature higher than or equal to an alteration temperature. In stepS12, however, the heating part 46 heats the particle retention layeronly up to a temperature lower than the alteration temperature under thecontrol of the controller 10. This enables maintaining the insolubilityof the solute component without causing alternation, while acceleratingthe volatilization of the solvent. The alteration temperature variesdepending on the type of the solute, and as shown in experimentalexamples, which will be described later, the alteration temperature canbe specified by experiment. Similarly, in the case where the particleretention layer is not heated, the insolubility of the solute componentis maintained without alternation.

DIW (Deionized water) is supplied onto the particle retention layer(step S13). Although the DIW is supplied by the rinsing liquid supplypart 443 in the present embodiment, a separate DIW supply part with thesame structure as that of the rinsing liquid supply part 443 may beprovided additionally. The supply of the DIW to the particle retentionlayer improves the hydrophilic property of the particle retention layer.To supply the DIW, the second nozzle 454 is moved to the center of theupper face 91 of the rotating substrate 9, and the DIW is supplied fromthe second nozzle 454 to the center of the upper face 91. The DIW issupplied not in spray form, but in the form of liquid columns or in theform of droplets that naturally drop from the nozzle. The DIW dispersedfrom the rotating substrate 9 is received by the cup 43. In step S13,the second nozzle 454 may swing in the horizontal direction. Note thatthe supply of the DIW to the particle retention layer may be omitted.

Next, the removal liquid supply part 442 supplies a removal liquid tothe particle retention layer on the substrate 9 (step S14).Specifically, the second nozzle 454 is moved to the center of the upperface 91 of the substrate 9, and the removal liquid is supplied from thesecond nozzle 454 to the center of the upper face 91 while the substrate9 is rotated at 500 to 800 rpm, for example. The removal liquid issupplied not in spray form, but in the form of liquid columns or in theform of droplets that naturally drop from the nozzle. The removal liquidis dispersed from the outer edge of the substrate 9 and received andcollected by the cup 43. In the present embodiment, an aqueous solutionused in SC-1 cleaning (hereinafter, referred to as an “SC-1 solution”),i.e., an aqueous solution of ammonia and hydrogen peroxide, is used asthe removal liquid. Alternatively, the removal liquid may be an aqueousammonia solution.

Here, as described previously, the solute component of the particleretention layer is insoluble in water. That is, the solute componentaccording to the present embodiment is insoluble in the removal liquid.On the other hand, the solvent remaining in the particle retention layeris soluble in water. That is, the solvent according to the presentembodiment is soluble in the removal liquid. Accordingly, by supplyingthe removal liquid to the particle retention layer without the need forthe process of altering the solute component of the particle retentionlayer, the solvent component of the particle retention layer can beremoved together with the remaining solvent from the substrate 9 whileretaining particles and without being dissolved in the removal liquid.At this time, the solute component is assumed to be removed in a largenumber of fine clusters due to the influence of the solvent remaining inthe particle retention layer. As a result, particles will not bedischarged from the particle retention layer onto the substrate 9 aswill be described later, and a high particle removal rate can beachieved. Note that, if the solute component of the particle retentionlayer can be removed with the removal liquid, the solvent does notnecessarily have to remain in the particle retention layer.

The rinsing liquid supply part 443 further supplies a rinsing liquidonto the substrate 9 (step S15). In the present embodiment, DIW is usedas the rinsing liquid. The DIW is supplied from the second nozzle 454 tothe center of the upper face 91 of the rotating substrate 9. The rinsingliquid is supplied not in spray form, but in the form of liquid columnsor in the form of droplets that naturally drop from the nozzle.Simultaneously at this time, the DIW is also supplied from the lowernozzle 456 to the center of the lower face 92 of the substrate 9. TheDIW dispersed from the substrate 9 is received by the cup 43. In stepsS14 and S15, the second nozzle 454 may swing in the horizontaldirection. Then, the supply of the DIW is stopped, and the substrate 9is further rotated so as to be dried (step S16). The substrate 9 may bedried by other techniques such as supplying dry gas, decompression, orheating.

In the substrate cleaning apparatus 4, processes from supplying theprocessing solution to the substrate 9 to supplying the removal liquidto the substrate 9 are performed while the substrate 9 is held by thesame substrate holder 42. That is, this processing is performed withoutthe substrate 9 being transported out of the chamber 47. This minimizesthe space for installation of the substrate cleaning apparatus 4. In thepresent embodiment, processes up to drying are performed while thesubstrate 9 is held by the substrate holder 42. Processing the substrate9 that is held by the substrate holder 42 means that the substrate 9 isprocessed within the chamber 47.

In the above-described series of processing, the substrate 9 is heatedbut not up to the alteration temperature, or the substrate 9 is notheated. This allows the substrate cleaning apparatus 4, which performsprocessing within the same chamber, to be designed more easily than inthe case where the substrate 9 is heated to a temperature exceeding thealteration temperature. Moreover, the possibility of particles adheringto the substrate 9 can be reduced by performing the series of processingwithin the same chamber.

FIG. 5 is a diagram for describing that the solute component of theparticle retention layer formed in the present embodiment has theproperty of becoming water-soluble by heating. FIG. 5 illustrates theresults of measurement using the QCM (quartz crystal microbalance)method. In this experiment, a film of gold was formed on a quartzoscillator and a particle retention layer was formed thereon. Then, theparticle retention layer was immersed in an SC-1 solution and oscillatedby the oscillator. According to the QCM method, the oscillationfrequency increases as the particle retention layer adhering to the filmof gold increases in mass.

Lines designated by reference signs 811, 812, 813, and 814 respectivelyindicate results in the cases where the particle retention layer washeated to 250° C., 200° C., 150° C., and 100° C., and a line designatedby a reference sign 815 indicates a result in the case where theparticle retention layer was not heated. The alteration temperature ofthe particle retention layer was approximately 200° C., and in the casewhere the particle retention layer was heated to 250° C. and 200° C.,the frequency became high, and this shows that the particle retentionlayer dissolved in the SC-1 solution. It can also be seen that in thecase where the particle retention layer was heated to 150° C. or less,the particle retention layer kept adhering to the top of the film ofgold and did not dissolve in the solution.

FIG. 6 illustrates the results of measuring the removal rate ofparticles with a predetermined particle diameter or more in the casewhere SiO₂ particles were caused to adhere to the top of an Si substrateand the cleaning illustrated in FIG. 3 was performed. Hereinafter, theparticle removal rate is expressed as “PRE.” To be precise, otherprocessing such as pre-processing is added to the processing illustratedin FIG. 3. The results for the cases in which the particle retentionlayer was not heated (at room temperature) in step S12 and in which theparticle retention layer was heated to 60° C., 80° C., 100° C., 150° C.,and 200° C. in step S12 are shown in order from the left. The roomtemperature was, for example, higher than or equal to 20° C. and lowerthan or equal to 30° C. The broken line indicates the PRE in the casewhere the cleaning was performed using only the SC-1 solution, and thePRE was 39%.

In any case, it can be seen that higher PREs were achieved than in thecase where the cleaning was performed using only the SC-1 solution. Notethat in the case where the particle retention layer was heated to 200°C., the solute component of the particle retention layer was dissolved,and therefore, the PRE decreased slightly from that in the case wherethe particle retention layer was heated to 150° C.

FIG. 7 illustrates the results of measuring the PRE for particles with apredetermined particle diameter or more in the case where PSL(polystyrene latex) particles were caused to adhere to the top of an Sisubstrate and the same cleaning as that in FIG. 6 was performed. Theresults for the cases in which the particle retention layer was notheated (at room temperature) in step S12 and in which the particleretention layer was heated to 100° C. in step S12 are shown in orderfrom the left. Note that the particle retention layer was heated to 120°C. when the PSL particles are caused to adhere to the substrate. Thebroken line indicates the PRE in the case where the cleaning wasperformed using only the SC-1 solution, and the PRE was 0.8%. In eithercase, it can be seen that much higher PREs were achieved than in thecase where the cleaning was performed using only the SC-1 solution.

FIG. 8 illustrates the results of measuring the PRE for particles with apredetermined particle diameter or more in the case where SiO₂ particleswere caused to adhere to the top of an SiN substrate and the samecleaning as that in FIG. 6 was performed. The results for the cases inwhich the particle retention layer was not heated (at room temperature)in step S12 and in which the particle retention layer was heated to 60°C., 100° C., 150° C., 200° C. in step S12 are shown in order from theleft. The broken line indicates the PRE in the case where the cleaningwas performed using only the SC-1 solution, and the PRE was 39.9%.

In any case, it can be seen that higher PREs were achieved than in thecase where the cleaning was performed using only the SC-1 solution. Notethat in the case where the particle retention layer was heated to 200°C., the solute component of the particle retention layer was dissolved,and therefore, the PRE decreased significantly from that in the casewhere the particle retention layer was heated to 150° C.

FIG. 9 illustrates the results of measuring the PRE for particles with apredetermined particle diameter or more in the case where PSL particleswere caused to adhere to the top of an SiN substrate and the samecleaning as that in FIG. 6 was performed. The results for the cases inwhich the particle retention layer was not heated (at room temperature)in step S12 and in which the particle retention layer was heated to 60°C., 100° C., and 150° C. in step S12 are shown in order from the left.The broken line indicates the PRE in the case where the cleaning wasperformed using only the SC-1 solution, and the PRE was 0.5%. In anycase, it can be seen that much higher PREs were achieved than in thecase where the cleaning was performed using only the SC-1 solution.

It can be seen from FIGS. 6 to 9 that the cleaning method according tothe present embodiment can achieve a high PRE without depending on thetype of the substrates 9.

FIG. 10 illustrates the results of yet another measurement of the PRE. Aline designated by a reference sign 821 indicates a relationship betweenthe heating temperature and the PRE in the case where the particleretention layer was formed to a thickness of 30 nm on a substrate withno pattern. A line designated by a reference sign 822 indicates arelationship between the heating temperature and the PRE in the casewhere the particle retention layer was formed to a thickness of 30 nm ona substrate with a pattern. A line designated by a reference sign 831indicates a relationship between the heating temperature and the PRE inthe case where the particle retention layer was formed to a thickness of75 nm on a substrate with no pattern. A line designated by a referencesign 832 indicates a relationship between the heating temperature andthe PRE in the case where the particle retention layer was formed to athickness of 75 nm on a substrate with a pattern. In any case, SiO₂particles were used as particles.

It can be seen from FIG. 10 that, in the case where the heatingtemperature was 200° C., the PRE became lower than that in the casewhere the heating temperature was 150° C. In particular, in the casewhere the substrate had a pattern, the PRE decreased sharply if theparticle retention layer was heated to 200° C. and became soluble in theremoval liquid. In FIG. 10, the PRE decreased in the cases where theheating temperature was lower than 150° C. This might have been causeddue to insufficient volatilization of the solvent.

From the above, it can be said that the PRE can be improved byintentionally maintaining the insolubility of the solute component ofthe particle retention layer in the removal liquid, rather than bydissolving the solute component in the solution. Also, by heating theparticle retention layer at a temperature as high as possible withoutcausing alteration, the particle retention layer can be efficientlycaused to solidify or harden, a high PRE can be achieved within a shorttime. This technique is in particular suitable for the cleaning of asubstrate 9 having a pattern. Also, the pattern is less damaged than inconventional physical cleaning using a spray of SC-1 solution.

FIG. 11A is a conceptual diagram illustrating a particle retention layer901 formed on a substrate 9. The particle retention layer 901 retainsparticles 902 adhering to the top of the substrate 9 so as to surroundthe particles 902. The particle retention layer 901 strips the particles902 off from the surface of the substrate 9 when the solvent isvolatilized from the processing solution and the solute componentshrinks. Note that not only the solute component shrinks due to thevolatilization of the solvent, but also the solute component itselfpreferably has the property of further shrinking due to other factors.Examples of the other factors include natural shrinkage of the solutecomponent itself, shrinkage due to heating, and chemical changes.

Since, as described previously, the solute component of the particleretention layer 901 is insoluble in the removal liquid, when the removalliquid is supplied to the substrate 9, the particle retention layer 901is considered to be divided into fine pieces 903 by the physical forcereceived from the removal liquid and be removed from the substrate 9 asillustrated in FIG. 11B. Accordingly, the particles 902 are removed fromthe substrate 9 without being discharged from the particle retentionlayer 901. In particular, since the solvent is soluble in the removalliquid, it is conceivable that the solvent remaining between thesubstrate 9 and the particle retention layer 901 will facilitate thestripping of the particle retention layer 901 from the substrate 9.

In the case where the particle retention layer having no alterationtemperature is stripped off from a substrate without being dissolved inthe solution, it is difficult to strip the particle retention layer offfrom a substrate that has a pattern, as described in Japanese PatentApplication Laid-Open Gazette No. 2015-95583. The reason for this isconsidered to be because the particle retention layer remains in largeclusters on the substrate. However, the inventors of the presentinvention have found that this problem does not occur if the particleretention layer (to be precise, its solute component) has an alterationtemperature. In this case, the particle retention layer is considered tobe divided into fine pieces that cannot be observed by the naked eye,and removed from the substrate even if the particle retention layer isnot dissolved in the solution. Thus, particles can be removedefficiently from even a substrate that has a pattern.

Since the removal liquid is ejected tenderly from the nozzle, theremoval liquid is supplied in the form of liquid columns or largedroplets onto the substrate 9. Therefore, the pattern is less damagedthan in the case where a cleaning liquid is supplied vigorously in sprayform to a substrate 9 as in conventional technology.

The above-described embodiment achieves a high PRE without intentionallyheating the processing solution that becomes soluble in the removalliquid when heated to the alteration temperature, or by using theprocessing solution that is heated to a temperature lower than thealteration temperature and exceeding the room temperature. This effectuses the property that the particle retention layer that is altered byheating can be removed with the removal liquid.

On the other hand, the property that the particle retention layer can bedivided into fine pieces in the removal liquid and removed from thesubstrate, irrespective of the fact that the solute component of theparticle retention layer is insoluble in the removal liquid, may beachieved by other factors. For example, in the case where part of thesolvent that is soluble in the removal liquid is not volatilized andremains in the particle retention layer, the removal of the insolublesolute component with the removal liquid, i.e., the removal of theparticle retention layer (to be precise, the solute component) with theremoval liquid, may be achieved by molecules of the removal liquidentering between molecules of the solute component. In this case, theproperty that the solute component becomes soluble in the removal liquidwhen heated is not an absolute necessity.

Although the heating part 46 of the substrate cleaning apparatus 4illustrated in FIG. 2 uses the heating plate 461 to heat the substrate9, i.e., to heat the particle retention layer, various other techniquescan be employed to heat the particle retention layer. For example, thesubstrate 9 may be heated with light emitted from a lamp. A face of thesubstrate 9 that is to be heated may be the upper face 91, or may be thelower face 92. Alternatively, the particle retention layer may be heatedby bringing a heated plate into close proximity to the upper face 91 ofthe substrate 9. As another alternative, the particle retention layermay be heated by supplying heated DIW or any other liquid to thesubstrate 9 as will be described below.

Next, some other exemplary operations of the substrate cleaningapparatus 4 will be described. In a preferable exemplary operation,instead of step S12 in FIG. 3, the substrate 9 is heated, i.e., theparticle retention layer is heated, by supplying heated DIW to the lowerface of the substrate 9 held in a horizontal position as illustrated instep S12 a in FIG. 12. The particle retention layer is heated to atemperature higher than the room temperature and lower than 100° C. Theheating of the particle retention layer causes shrinkage of the particleretention layer. In the case of this exemplary operation, a heater thatpre-heats DIW ejected from the lower nozzle 456 is provided for theheating part 46, and the heater and the lower nozzle 456 function as theheating part 46.

In the case where the substrate 9 is heated with DIW, the heating plate461 can be omitted. By supplying heated DIW to the lower face of thesubstrate 9, the substrate 9 can be heated with a simple structure andwithout giving any influence on the upper face that is to be cleaned.The operations of the substrate cleaning apparatus 4 are the same asthose in FIG. 3, except that the particle retention layer is heated bysupplying heated DIW to the lower face of the substrate 9. Although thesupply of ordinary-temperature DIW in step S13 is desirably performed,this supply may be omitted.

As illustrated in step S12 b in FIG. 13, the substrate 9 may be heatedby supplying heated DIW to the upper face of the substrate 9 held in ahorizontal position. Step S12 b is a process that combines steps S12 andS13 in FIG. 3. In the case of this exemplary operation, a heater thatpre-heats DIW ejected from the second nozzle 454 is provided for theheating part 46. The heater and the second nozzle 454 function as theheating part 46. Since the substrate 9 is heated with the DIW, theheating plate 461 may be omitted. It is conceivable that the solventremaining in the particle retention layer is removed and the particleretention layer is heated by the supply of the heated DIW to the upperface of the substrate 9, thereby causing shrinkage of the particleretention layer.

Although, with the supply of the DIW, part of the solute component ofthe particle retention layer may be removed from the substrate 9, theparticle retention layer is normally not removed completely with theDIW, and therefore the DIW does not function as the removal liquid instep S14. The substrate 9 may be heated by supplying the heated DIW tothe upper and lower faces of the substrate 9 held in a horizontalposition. This operation is also a process that combines steps S12 andS13 in FIG. 3.

As illustrated in step S14 a in FIG. 14, instead of step S14 in FIG. 3,the removal liquid supply part 442 may supply a heated removal liquidonto the substrate 9. That is, the removal liquid that is heated up to atemperature lower than the alteration temperature is supplied to theupper face of the substrate 9 held in a horizontal position. Step S14 aalso serves as the process of heating the particle retention layer instep S12 in FIG. 3. Thus, normally step S12 is omitted. However, stepS14 a may be performed after execution of step S12.

In the case where the heated removal liquid is supplied, the supply ofthe DIW in step S13 may be performed, or may not be performed. In thecase where performing only step S14 a is not enough to heat the particleretention layer, the supply of the heated DIW in step S12 a illustratedin FIG. 12 and/or step S12 b illustrated in FIG. 13 may be performedbefore step S14 a. The supply of the heated removal liquid enablessimultaneous execution of the heating of the particle retention layerand the supply of the removal liquid.

FIGS. 15 to 17 are diagrams illustrating examples in which the particleretention layer is heated at the stage when the particle retention layeris formed. In step S11 a in FIG. 15, which is performed instead of stepS11 in FIG. 3, the processing solution supply part 441 supplies a heatedprocessing solution onto the substrate 9. That is, a processing solutionthat is heated up to a temperature lower than the alteration temperatureis supplied to the upper face of the substrate 9 held in a horizontalposition. This causes the solvent to be volatilized in parallel with theformation of the particle retention layer and accelerates the separationof particles from the substrate 9 due to shrinkage of the particleretention layer.

In step S11 b in FIG. 16, which is performed instead of step S11 in FIG.3, the heating of the substrate 9 and the supply of the processingsolution are performed in parallel. That is, the formation of theparticle retention layer and the heating of the particle retention layerare performed at the same time. During the formation of the particleretention layer, the particle retention layer shrinks due to thevolatilization and heating of the solvent. The heating of the substrate9 to a temperature lower than the alteration temperature is implementedby, for example, the heating part 46 in FIG. 2. The heating may beimplemented by other techniques such as irradiating the upper or lowerface of the substrate 9 with light emitted from a lamp, bringing aheated plate to the upper face of the substrate 9, or supplying heatedDIW to the lower face of the substrate 9 as described previously.

In steps S11 c and S11 d in FIG. 17, which are performed instead of stepS11 in FIG. 3, a processing solution is supplied after the substrate 9is heated. In other words, the substrate 9 is heated up to a temperaturelower than the alteration temperature before the supply of theprocessing solution. The heating of the substrate 9 to a temperaturelower than the alteration temperature in step S11 c is implemented by,for example, the heating part 46 in FIG. 2. The heating may beimplemented by supplying heated DIW as in FIGS. 12 and 13, or by othertechniques such as irradiating the upper or lower face of the substrate9 with light emitted from a lamp or bringing a heated plate to the upperface of the substrate 9 as described previously. Note that it ispossible to perform both of the process for heating the substrate 9before or during the supply of the processing solution and the processfor supplying the heated processing solution to the substrate 9.

In the case where the particle retention layer is heated almostsimultaneously with its formation as illustrated in FIGS. 15 to 17, theheating of the particle retention layer in step S12 and the supply ofthe heated DIW or the heated removal liquid are, in principle,unnecessary. However, these processes may be performed. It goes withoutsaying that ordinary-temperature DIW may be supplied to the upper faceof the substrate 9 in step S13.

Different heating parts may be used as the heating part configured toheat the particle retention layer in step S12 in FIG. 3 and the heatingpart configured to heat the particle retention layer in step S11 b inFIG. 16 and step S11 c in FIG. 17. For example, the substrate 9 may beheated with the heating plate 461 in step S11 b or S11 c and may beheated with the heated DIW in step S12. In other words, the heating partthat heats the substrate 9 before the supply of the removal liquid tothe substrate 9 and the heating part that heats the substrate 9 beforeor in parallel with the supply of the processing solution to thesubstrate 9 may be different heating parts, or may be the same heatingpart.

The substrate cleaning system 1 and the substrate cleaning apparatus 4described above may be modified in various ways.

The processing solution supply part 441 may supply the processingsolution by a different method other than ejecting the solution from thenozzle. The removal liquid supply part 442 and the rinsing liquid supplypart 443 may also supply the removal liquid and the rinsing liquid by adifferent method other than ejecting the liquids from the nozzles.Preferably, it is desirable to adopt techniques that cause less damageto the pattern on the surface of the substrate 9.

Yet another technique may be adopted to heat the particle retentionlayer by heating the substrate 9. For example, the substrate 9 may beheated by supplying high-temperature gas to the upper face 91 or lowerface 92 of the substrate 9.

The substrate 9 may be heated within another dedicated chamber.Moreover, the formation, heating, and removal of the particle retentionlayer may be performed within different chambers.

Although the solute component of the particle retention layer accordingto the present embodiment is changed from having insolubility to havingsolubility by being heated up to the alteration temperature, varioussolute components and removal liquids may be used as long as the solutecomponent can be changed from being insoluble in the removal liquid tobeing soluble in the removal liquid. Also, the solvent is not limited toa water-soluble solvent as long as it is soluble in the removal liquid.

The temperature to which the particle retention layer is heated may beany temperature that is lower than the alteration temperature, and maybe a temperature at which the particle retention layer changes to becomeslightly soluble in water. The solute component of the particleretention layer does not necessarily have to be completely insoluble inthe removal liquid, and may be poorly soluble in the removal liquid.

The volatile solvent contained in the processing solution is preferablyof an organic type, i.e., an organic compound, but it may contain othervolatile substances.

Although the solute according to the above-described embodiment ispolymer, the solute may be an organic compound other than polymer. Asanother alternative, the solute may be a mixture of an organic compoundand other substances, or may be a compound other than organic compounds.

The removal liquid is not limited to the SC-1 solution. Although the useof the SC-1 solution or the aqueous ammonia solution is desirable inorder to prevent the re-adhesion of the removed particle retentionlayer, other removal liquids may be used.

The cleaning process performed by the substrate cleaning apparatus 4 mayinclude other processes in addition to the processes described in theabove embodiment. For example, pre-processing or post-processing may beadded to each process.

The substrates 9 cleaned by the substrate cleaning system 1 are notlimited to Si substrates or SiN substrates, and may be othersemiconductor substrates. The substrates 9 are not limited tosemiconductor substrates, and may be other substrates such as glasssubstrates for liquid crystal displays, glass substrates for organic ELdisplays, glass substrates for plasma displays, optical disk substrates,magnetic disk substrates, magneto-optical disk substrates, glasssubstrates for photomasks, and substrates for solar cells.

The configurations of the preferred embodiments and variations describedabove may be appropriately combined as long as there are no mutualinconsistencies.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore to be understood that numerousmodifications and variations can be devised without departing from thescope of the invention.

REFERENCE SIGNS LIST

-   -   4 Substrate cleaning apparatus    -   9 Substrate    -   10 Controller    -   42 Substrate holder    -   46 Heating part    -   441 Processing solution supply part    -   442 Removal liquid supply part    -   901 Particle retention layer    -   S11 to S14, S11 a, S11 b, S11 c, S12 a, S12 b, S14 a Step

1. A substrate cleaning apparatus comprising: a processing solutionsupply part that supplies a processing solution containing solvent andsolute, onto a top of substrate; a removal liquid supply part thatsupplies a removal liquid onto said substrate; and a controller thatcontrols said processing solution supply part and said removal liquidsupply part, wherein said solvent has volatility, said processingsolution transforms into a particle retention layer as a result of atleast part of said solvent being volatilized from said processingsolution supplied onto said substrate and causing said processingsolution to solidify or harden, a solute component that is said solutecontained in said particle retention layer or that is derived from saidsolute is insoluble or poorly soluble in said removal liquid, and saidsolvent is soluble in said removal liquid, and after said particleretention layer is formed on said substrate, said controller controlssaid removal liquid supply part to supply said removal liquid to saidparticle retention layer, said particle retention layer being dividedinto fine pieces by a physical force received from said removal liquidwhile said particle retention layer is removed from the top of saidsubstrate.
 2. The substrate cleaning apparatus according to claim 1,further comprising: a heating part that heats said particle retentionlayer, wherein said solute component contained in said particleretention layer has a property of being altered to become soluble insaid removal liquid when heated to a temperature higher than or equal toan alteration temperature, and said controller controls said heatingpart to heat said particle retention layer up to a temperature lowerthan said alteration temperature before said removal liquid is suppliedto said particle retention layer.
 3. The substrate cleaning apparatusaccording to claim 2, wherein said processing solution supply partsupplies said processing solution to an upper face of said substrateheld in a horizontal position, and said heating part heats said particleretention layer by supplying heated deionized water to a lower face ofsaid substrate.
 4. The substrate cleaning apparatus according to claim2, wherein said processing solution supply part supplies said processingsolution to an upper face of said substrate held in a horizontalposition, and said heating part heats said particle retention layer bysupplying heated deionized water to the upper face of said substrate. 5.The substrate cleaning apparatus according to claim 1, wherein saidsolute component contained in said particle retention layer has aproperty of being altered to become soluble in said removal liquid whenheated to a temperature higher than or equal to an alterationtemperature, and said removal liquid supply part supplies said removalliquid that is heated up to a temperature lower than said alterationtemperature, onto said substrate.
 6. The substrate cleaning apparatusaccording to claim 1, wherein said solute component contained in saidparticle retention layer has a property of being altered to becomesoluble in said removal liquid when heated to a temperature higher thanor equal to an alteration temperature, and said processing solutionsupply part supplies said processing solution that is heated up to atemperature lower than said alteration temperature, onto said substrate.7. The substrate cleaning apparatus according to claim 1, furthercomprising a heating part, wherein said solute component contained insaid particle retention layer has a property of being altered to becomesoluble in said removal liquid when heated to a temperature higher thanor equal to an alteration temperature, and said heating part heats saidsubstrate up to a temperature lower than said alteration temperaturebefore or in parallel with the supply of said processing solution tosaid substrate.
 8. The substrate cleaning apparatus according to claim1, further comprising: a substrate holder that holds a substrate;wherein operations from supplying said processing solution to saidsubstrate to supplying said removal liquid to said substrate areperformed while said substrate is held by said substrate holder.
 9. Thesubstrate cleaning apparatus according to claim 1, further comprising asubstrate rotation mechanism, wherein said removal liquid is suppliedonto said substrate while said substrate is rotated by said substraterotation mechanism under control of said controller.
 10. A substratecleaning apparatus comprising: a processing solution supply part thatsupplies a processing solution containing solvent and solute, onto a topof substrate; a removal liquid supply part that supplies a removalliquid onto said substrate; and a controller that controls saidprocessing solution supply part and said removal liquid supply part,wherein said solvent has volatility, said processing solution transformsinto a particle retention layer as a result of at least part of saidsolvent being volatilized from said processing solution supplied ontosaid substrate and causing said processing solution to solidify orharden, a solute component that is said solute contained in saidparticle retention layer or that is derived from said solute isinsoluble or poorly soluble in said removal liquid, and said solvent issoluble in said removal liquid, and after said particle retention layeris formed on said substrate, said controller controls said removalliquid supply part to supply said removal liquid to said particleretention layer, molecules of said removal liquid entering betweenmolecules of said solute component where part of said solvent is notvolatilized and remains in said particle retention layer while saidparticle retention layer is removed from the top of said substrate. 11.The substrate cleaning apparatus according to claim 10, furthercomprising: a heating part that heats said particle retention layer,wherein said solute component contained in said particle retention layerhas a property of being altered to become soluble in said removal liquidwhen heated to a temperature higher than or equal to an alterationtemperature, and said controller controls said heating part to heat saidparticle retention layer up to a temperature lower than said alterationtemperature before said removal liquid is supplied to said particleretention layer.
 12. The substrate cleaning apparatus according to claim11, wherein said processing solution supply part supplies saidprocessing solution to an upper face of said substrate held in ahorizontal position, and said heating part heats said particle retentionlayer by supplying heated deionized water to a lower face of saidsubstrate.
 13. The substrate cleaning apparatus according to claim 11,wherein said processing solution supply part supplies said processingsolution to an upper face of said substrate held in a horizontalposition, and said heating part heats said particle retention layer bysupplying heated deionized water to the upper face of said substrate.14. The substrate cleaning apparatus according to claim 10, wherein saidsolute component contained in said particle retention layer has aproperty of being altered to become soluble in said removal liquid whenheated to a temperature higher than or equal to an alterationtemperature, and said removal liquid supply part supplies said removalliquid that is heated up to a temperature lower than said alterationtemperature, onto said substrate.
 15. The substrate cleaning apparatusaccording to claim 10, wherein said solute component contained in saidparticle retention layer has a property of being altered to becomesoluble in said removal liquid when heated to a temperature higher thanor equal to an alteration temperature, and said processing solutionsupply part supplies said processing solution that is heated up to atemperature lower than said alteration temperature, onto said substrate.16. The substrate cleaning apparatus according to claim 10, furthercomprising a heating part, wherein said solute component contained insaid particle retention layer has a property of being altered to becomesoluble in said removal liquid when heated to a temperature higher thanor equal to an alteration temperature, and said heating part heats saidsubstrate up to a temperature lower than said alteration temperaturebefore or in parallel with the supply of said processing solution tosaid substrate.
 17. The substrate cleaning apparatus according to claim10, further comprising: a substrate holder that holds a substrate;wherein operations from supplying said processing solution to saidsubstrate to supplying said removal liquid to said substrate areperformed while said substrate is held by said substrate holder.
 18. Thesubstrate cleaning apparatus according to claim 10, further comprising asubstrate rotation mechanism, wherein said removal liquid is suppliedonto said substrate while said substrate is rotated by said substraterotation mechanism under control of said controller.
 19. A substratecleaning method comprising: a) supplying a processing solutioncontaining solvent and solute, onto a top of substrate; and b) supplyinga removal liquid onto said substrate, wherein said solvent hasvolatility, in said operation a), said processing solution transformsinto a particle retention layer as a result of at least part of thesolvent being volatilized from said processing solution supplied ontosaid substrate and causing said processing solution to solidify orharden, a solute component that is said solute contained in saidparticle retention layer or that is derived from said solute isinsoluble or poorly soluble in said removal liquid, and said solvent issoluble in said removal liquid, and in said operation b) after saidoperation a), said particle retention layer is divided into fine piecesby a physical force received from said removal liquid while saidparticle retention layer is removed from the top of said substrate. 20.The substrate cleaning method according to claim 19, wherein said solutecomponent contained in said particle retention layer has a property ofbeing altered to become soluble in said removal liquid when heated to atemperature higher than or equal to an alteration temperature, and saidsubstrate cleaning method further comprising: c) heating said particleretention layer up to a temperature lower than said alterationtemperature, between said operation a) and said operation b).
 21. Thesubstrate cleaning method according to claim 20, wherein in saidoperation a), said processing solution is supplied to an upper face ofsaid substrate held in a horizontal position, and in said operation c),said particle retention layer is heated by supplying heated deionizedwater to a lower face of said substrate.
 22. The substrate cleaningmethod according to claim 20, wherein in said operation a), saidprocessing solution is supplied to an upper face of said substrate heldin a horizontal position, and in said operation c), said particleretention layer is heated by supplying heated deionized water to theupper face of said substrate.
 23. The substrate cleaning methodaccording to claim 19, wherein said solute component contained in saidparticle retention layer has a property of being altered to becomesoluble in said removal liquid when heated to a temperature higher thanor equal to an alteration temperature, and in said operation b), saidremoval liquid that is heated up to a temperature lower than saidalteration temperature is supplied onto said substrate.
 24. Thesubstrate cleaning method according to claim 19, wherein said solutecomponent contained in said particle retention layer has a property ofbeing altered to become soluble in said removal liquid when heated to atemperature higher than or equal to an alteration temperature, and insaid operation a), said processing solution that is heated up to atemperature lower than said alteration temperature is supplied onto saidsubstrate.
 25. The substrate cleaning method according to claim 19,wherein said solute component contained in said particle retention layerhas a property of being altered to become soluble in said removal liquidwhen heated to a temperature higher than or equal to an alterationtemperature, and said substrate is heated up to a temperature lower thansaid alteration temperature before or during said operation a).
 26. Thesubstrate cleaning method according to claim 19, wherein operations fromsupplying said processing solution to said substrate to supplying saidremoval liquid to said substrate are performed while said substrate isheld by a same substrate holder.
 27. The substrate cleaning methodaccording to claim 19, wherein said removal liquid is supplied onto saidsubstrate while said substrate is rotated in said operation b).
 28. Asubstrate cleaning method comprising: a) supplying a processing solutioncontaining solvent and solute, onto a top of substrate; and b) supplyinga removal liquid onto said substrate, wherein said solvent hasvolatility, in said operation a), said processing solution transformsinto a particle retention layer as a result of at least part of thesolvent being volatilized from said processing solution supplied ontosaid substrate and causing said processing solution to solidify orharden, a solute component that is said solute contained in saidparticle retention layer or that is derived from said solute isinsoluble or poorly soluble in said removal liquid, and said solvent issoluble in said removal liquid, and in said operation b) after saidoperation a), molecules of said removal liquid enter between moleculesof said solute component where part of said solvent is not volatilizedand remains in said particle retention layer while said particleretention layer is removed from the top of said substrate.
 29. Thesubstrate cleaning method according to claim 28, wherein said solutecomponent contained in said particle retention layer has a property ofbeing altered to become soluble in said removal liquid when heated to atemperature higher than or equal to an alteration temperature, and saidsubstrate cleaning method further comprising: c) heating said particleretention layer up to a temperature lower than said alterationtemperature, between said operation a) and said operation b).
 30. Thesubstrate cleaning method according to claim 29, wherein in saidoperation a), said processing solution is supplied to an upper face ofsaid substrate held in a horizontal position, and in said operation c),said particle retention layer is heated by supplying heated deionizedwater to a lower face of said substrate.
 31. The substrate cleaningmethod according to claim 29, wherein in said operation a), saidprocessing solution is supplied to an upper face of said substrate heldin a horizontal position, and in said operation c), said particleretention layer is heated by supplying heated deionized water to theupper face of said substrate.
 32. The substrate cleaning methodaccording to claim 28, wherein said solute component contained in saidparticle retention layer has a property of being altered to becomesoluble in said removal liquid when heated to a temperature higher thanor equal to an alteration temperature, and in said operation b), saidremoval liquid that is heated up to a temperature lower than saidalteration temperature is supplied onto said substrate.
 33. Thesubstrate cleaning method according to claim 28, wherein said solutecomponent contained in said particle retention layer has a property ofbeing altered to become soluble in said removal liquid when heated to atemperature higher than or equal to an alteration temperature, and insaid operation a), said processing solution that is heated up to atemperature lower than said alteration temperature is supplied onto saidsubstrate.
 34. The substrate cleaning method according to claim 28,wherein said solute component contained in said particle retention layerhas a property of being altered to become soluble in said removal liquidwhen heated to a temperature higher than or equal to an alterationtemperature, and said substrate is heated up to a temperature lower thansaid alteration temperature before or during said operation a).
 35. Thesubstrate cleaning method according to claim 28, wherein operations fromsupplying said processing solution to said substrate to supplying saidremoval liquid to said substrate are performed while said substrate isheld by a same substrate holder.
 36. The substrate cleaning methodaccording to claim 28, wherein said removal liquid is supplied onto saidsubstrate while said substrate is rotated in said operation b).